Method of making straps



S. SHAPIRO METHOD OF MAKING STRAPS ,July' 5 1927. 1,634,562

Filed May 20. 1926 M 20 O? 5 Z6 J? "117 J I 1-9 -INVENTOR jaul v BY 4 /5 2/ ATTORNEY Patented July 5, 1927.

UNITED STATES PATENT OFFICE-Q SAUL SHAPIRO, OF NEW YORK, 1\T. Y., ASSIGNOR- TO ARTCRAFT METAL STAMPING COR- 7 PORATION, CORPORATION. OF NEW YORK.

METHOD or MAKING STRAPS.

Application filed May 20,

The present invention relates to methods of making straps and is more particularly directed toward a method of manufacture to be employed in making straps having 5 thickening ribs along both edges and both sides of the strap.

The invention is more particularly directed toward the manufacture of a strap which may be bent to various shapes suitable for use in manufacturing lighting fixtures.

It has been common in the art to make up lighting fixtures using castings of brass, aluminum, or iron or bent straps of fiat stock, generally of strap iron. Thin cast ings such as are suitable for straps are difficult to cast and are generally unfinished on one side. In most cases, the cross section of the strap iron is rectangular, and in order to suitably ornament fixtures so made, it has been necessary'to apply leaves, 7 flowers, rosettes, and the like to overcome the otherwise bare or naked appearance of the straps. A number of these ornaments were sometimes required for each strap. As these straps are bent in various manners, both sides of the strap are visible, and considerable difficulty may be found in providing suitable ornaments on both sides of the strap. Certain finishes, such as silver and gold which may be applied to brass, cannot be satisfactorily applied to iron. Various other difficulties have arisen in the manufacture of high class fixtures of this type, which are overcome by utilizing the strap made up according to the present invention. This new form of strap also improves the appearance of the fixture.

The present invention contemplates a method by which one may economically convert a flat strip of sheet metal into a narrow strap having thickening ribs along both edges and both sides, the'material between the ribs and forming the body of the strap, being of the same thickness as the sheet.

According to the method employed, the inarg'inal portions of the strip of sheet metal are folded to form the thickening ribs and compressed into intimate contact with one another so that the completed strap appears to be without seams. 7

According to the method which will be described in detail in the specification, a

1926. Serial No. 110,490.

fiat strip of sheet metal, such as brass, is subjected to a number of stamping operations to convert it to approximately the shape desired, and then is passed through a pair of rollers which complete the shape of the strap. It may, if desired, be then passed through another pair of rollers which impress ornamental detail into the strap. The entire method may be carried out by rolling instead of stamping The accompanying drawings show, for' purposes of illustration, a series of steps by which one may manufacture the strap hav ing the above characteristics, out of a fiat strip of sheet metal, it being understood that these drawings are illustrative of the invention rather than limiting the same.,

In these drawings:

Figures 1 to 5, inclusive, are perspective views illustrating the fiat blank, the completed strap, and the intermediate steps through which it passes; 7

Figure 6 is a sectional view illustrating a pair of cooperative punchand die mechanisms used in passing from the flat blank of Figure 1 to the channel shaped section of Figure 2;

Figure 7 is a similar view illustrating the pair used in making the section shown in Figure 3;

Figure 8 is a similar view showing the pair used in making a section of Figure 4;

Figure 9 illustrates a form of rolls used in making the finished shape shown in Figure 5;

Figure 10 is an enlarged view showing the completed strap of Figure 5 having'impressed in it diagonal corrugations to simulate rope; and

' Figure 11 is'a perspective view of a fragment of abent lighting fixture strap made up according to the present invention.

A strip of sheet metal 15 is shown in Figure 1. This strip of metal is of the de sired width and of the thickness which is desired for the body of the strap, and the Width and thickness are so selected so that the strap will have the desired portions without wasting or unnecessarily working the materials. The edges of the strip are straight and true and free of burrs.

The flat strip is placed in a stamping machine and" is acted upon by cooperative punch and die mechanisms, such as shown in Figure 6, to convert it into a channel shaped member 16 shown in Figures 2 and 6. As shown in Figure 6, the punch 17 has a depressed working face 18, while the cooperative die, shown at 19, is provided with a knockout 20. The working faces of this cooperative pair are such that the flat strip of sheet metal is brought to the channelshaped form, indicated at 16, and having a bottom 21, side walls 22 and rounded corners 23. These rounded corners are preferably made by the rounded working surfaces 2% and 25 in the punch and knockout. The punch and die mechanism of Figure 6 does not thin the metal.

In passing from the stage indicated in Figures 2 and 6 to the stage indicated in Figures 3 and 7, the channel-shaped strip 16 is inverted and placed on a die 26 having curved recesses in its upper working face as indicated at 27. The knockout at 28 in thisset of dies is narrower than the spacing of the sides 22 of the channel form strip 16 so that the metal which forms the sides of the channel is forced against the curved recesses 27 and formed into the arc-shaped side walls 29 as shown in Figures 3 and 7. The punch 30 has a flat working surface 31. In this operation, the ends of the side walls 22 of the channel section of Figure 2 will first rest on the outer part of the curved working faces 27. lVhen the press is closed the side walls are forced around the curved working surfaces and brought to the shape indicated, without thinning of the metal, thereby making strip 32.

In passing from the stage indicated in Figures 3 and 7 to the stage indicated in Figures l and 8, the strip 32 is again inverted and placed between the cooperative punches and dies shown in Figure 8. In this case, the punch 83 has a. pair of longitudinal substantially semi-circular channels 34 in its working face, while the die 35 is provided with somewhat similarly shaped channels 36 which are cut deeper into the face of the die. The knockout 37 is arranged as indicated. The flat lower side of the strip rests on the upper face 38 of the knockout 37. The width of this knockout is the width of the body of the finished strap which is to be made. VJhen the press is closed, the grooves 3 st in the punch 33 engage the upper edges of the arc-shaped side walls of the strip and force these side walls and the adjacent portion of the channel shaped member downwardly into the channels 36 in the die so as to bring the strip into the section indicated in Figures 4: and 8. It will be noted that in this operation the central body part of the strip 39 has been raised relative to the unfinished ribs 44) and that the side walls 41 of the strip have been forced nearly into closed position and with their free edges 4-2 comparatively near the upper surface of the body portion 39 of the strip. The channels 36 are preferably so shaped that the corners formed at 13 in the strip are very sharp.

The strip having the form shown in Figure 4 is next passed through a pair of rolls 45 and 46 as indicated in Figure 9. These rolls form the strip of the cross section shown in Figures 5 and 10. In this opera tion, the edges 42 of the original sheet are forced down against the upper surface 44 of the sheet as indicated. The rolls compress the material as indicated in Figure 10 so that the desired ribs 50, 51, 52 and 53 are formed along the strip. These, it will be noted, are arranged symmetrically relative to the axis of the strip. The rolls have compressed the material in these ribs so tightly together, that one cannot observe a seam and so that parts do not open up when the strip of Figure 10 is bent to form lighting fixture straps such as indicated at 54 of Figure 11.

After the strip has been rolled to the shape indicated in Figures 5 and 10, it may be suitably ornamented by passing it through. another set of rolls. For instance, in Figure 10, it is shown as having been passed through a set of rolls which provide corrugations or cuts 55 that simulate rope. Other forms of ornamentation such as dim ples, criss-cross marks stripes or the like, may be provided if desired.

rrccording to the method above outlined in considerable detail, the process is carried out by utilizing a stamping machine for several of the stages and rolls for the last stage. It will, of course be understood that this n'zethorl is only illustrative of the method for converting the flat strip of metal into the finished strap of the doubled channel shaped cross section. The operations, when carried out in a press, are preferably carried out on strips of metal long enough to make one or more complete straps for the lighting fixture which is being constructed so as to avoid waste of materials. The dou ble channel cross section strap such as shown in Figure 10, may be bent readily to any ornamental shape desired, and thereby provide curved straps, arms or the like for light ing fixture straps or other devices, which possess greater ornamentation than is possible in the flat strip that is ordinarily used in the same construction. The process of manufacture above described, requires comparatively a small amount of power. The metal is not thinned. extruded or drawn out. It is of course obvious that there is no waste.

lVhen these straps are made of'brass, it is possible to readily attach ornamentation by soldering, brazing, screws or the like and it is possible to treat the metal as brass may be treated, thereby making. it possible to manufacture lighting fixtures with greater facility than where iron straps are used, and also making it possible to provide fixtures having ornamentation along the entire length of the .strap. t

The usefulness of these straps for manufacturing, lighting fixtures is treated more fully in my copending application, Serial for lighting.

Nat an; filed March a, .1926 fixtures. V

hat is claimed is:

1. The method ofrmaking a readily bendable metallic strip, comprising bending up an edge ofthe strip,then turning it inward- 1y and'compacting it into a substantially solid mass of metal to form a thickened, rounded solid rib .extending along an edge of the strip, the strip being bendable without distortion of the rib.

2. The method of making a readily bendable metallic strip, comprising bending up both longitudinal edges of the strip, then turning the edges in toward each other and compacting them into a substantially solid mass of metal, for forming symmetrically disposed solid ribs extending along the edges of the strip, the strip being bendable without distortion of the rib.

3. The method of converting a flat strip of sheet metal into a narrower strap having substantially solid thickening ribs along both edges and both sides, the material between the ribs and forming the body of the strap being of the same thickness as the sheet, which consists in folding the marginal portions of the strip to form substantially solid thickening ribs, and passing it through rolls which arrange the thickening ribs symmetrically relative to the axes of the strap, the strap and ribs being bendable into vari ous shapes without collapse.

4. The method of converting a flat strip of sheet metal into a narrower strap having substantially solid thickening ribs along both edges and both sides, the, material between the ribs and forming the body of the strap being of the same thickness as the sheet, which consists'in stamping the strap into a shallow channel-shaped cross section,

forcing inwardly the free edges of the channel walls, pressing upwardly the bottom of the channel to initiate the formation of ribs at one side of both edges of the strip, and then rolling the strip to cause the remainder of the channel walls to form the other rib and symmetrically arrange all the ribs relative to the axes of the strap, the ribs being solid throughout, and the strap being bendable into various shapes without collapse of the ribs.

5. The method of converting a flat strip of sheet metal into a narrower strap having thickening ribs along both edges and both sides, the material between the ribs and forming the body of the strap being of the same thickness as the sheet, which consists in stamping the strap into a shallow channel-shaped cross section, forcing inwardly the free edges of the channel walls, pressing upwardly the bottom of the channel to initiatethe formation of ribs at one side of both edges of the strip, then rolling the strip to cause the remainder of the channel walls to form'theother rib and syinmetri-' cally arrange all the ribs relative to the axes of the strapv the ribs being substantially solid throughout and thereafter rolling indentations into the ribs.

6. The method of converting a flat strip of sheet metal into a narrower strap having thickening ribs along both edges and both sides, the. material between. the ribs and forming the body of the strap being of the same thickness as the sheet, which consists in bringing the side edges of the strip flat against a face of the strip and forming the marginal'portions of the strip into thickening ribs which are substantially solid throughout, the strap with the ribs being readily bendable without collapse of the ribs.

7. The method of converting a flat strip of sheet metal into a narrower strap having thickening ribs along both edges and both sides, the material between the ribs and forming the body of the strap being of the same thickness as the sheet, which consists in bringing the side edges of the strip flat against a face of the strip and forming the marginal portions ofthe strip into the thickening ribs, and compressing the material of the ribs into intimate contact to form substantially solid ribs, which do not collapse on bending.

8. The method of converting a flat strip of sheet metal into a narrower strap having thickening. ribs along both edges and both sides, the material between the ribs and forming the body of the strap being of the same thickness as the sheet, which consists in deforming each marginal portion of the strip so that it is doubled onto itself with the doubled part adjacent the body of the strip and at one side of the body and so that the 1 edge of the strip is adjacent the other side of the body, and rolling the edge of the strip against the face of the body to form ribs which are a substantially solid mass of metal, and which do not collapse on bending.

9. The method of converting a flat strip of sheet metal intoa narrower strap having thickening ribs along both edges and both sides, the material between the ribs and forming the body of the strap being of the same thickness as the sheet, which consists in deforming each marginal portion of the strip so that it is doubled onto itself with the doubled part adjacent the body of the strip and at one side of the body and so that the edge of the strip is adjacent the other side of the body, rolling the edge 01'? the strip against the face of the body to form the ribs, and then compressing the material of the ribs into intimate contact whereby the ribs are substantially solid throughout, and do not collapse on bending.

10. The method which consists in operating on a channel shaped strip of sheet metal having inwardly curved sides by pressing the sile walls and adjacent metal of the bottom of the channel downward relative to the remainder of the metal of the channel bottom to form a pair of ribs of double thickness on both edges of the strip and a projecting edge of single thickness on the other side of the strip the ribs being of substantially solid metal, which maintains its shape and does not collapse on bending.

11. The method which consists in operating on a channel shaped strip of sheet metal having inwardly curved sides by pressing the side Walls and adjacent metal of the bottom of the channel downward relative to the remainder of the metal of the channel bottom to form a pair of ribs of double thickness on both edges of the strip and a projecting edge of single thickness on the other side oi the strip, and rolling each projecting edge onto itself to form a substantially solid rib of double thickness the solidity of the ribs preventing their collapse on bending.

SAUL SHAPIRO. 

